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help / color / mirror / Atom feedFrom: Pierre Forstmann <pierre.forstmann@gmail.com>
To: pierre@senellart.com
To: pgsql-bugs@lists.postgresql.org
Subject: Re:[patch] BUG #19558: User-defined prefix operators "|" and "->" no longer parse in 19beta2 (SQL/PGQ grammar change)
Date: Sat, 18 Jul 2026 17:38:41 +0200
Message-ID: <02aea982-c656-462d-a412-1fb2e388f754@gmail.com> (raw)
In-Reply-To: <19558-ad1fca59a3a471a0@postgresql.org>
References: <19558-ad1fca59a3a471a0@postgresql.org>
Hello,
I propose following patch that adds missing grammar rules:
src/backend/parser/gram.y | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e138..331da79 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -15873,6 +15873,10 @@ a_expr: c_expr { $$ =
$1; }
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", NULL,
$2, @1); }
| '-' a_expr %prec UMINUS
{ $$ = doNegate($2, @1); }
+ | '|' a_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", NULL ,
$2, @1); }
+ | RIGHT_ARROW a_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "->", NULL
, $2, @1); }
| a_expr '+' a_expr
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", $1,
$3, @2); }
| a_expr '-' a_expr
@@ -15902,6 +15906,7 @@ a_expr: c_expr { $$ = $1; }
| a_expr '|' a_expr
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", $1,
$3, @2); }
+
| a_expr qual_Op a_expr %prec Op
{ $$ = (Node *) makeA_Expr(AEXPR_OP, $2, $1, $3, @2); }
| qual_Op a_expr %prec Op
@@ -16355,6 +16360,10 @@ b_expr: c_expr
{ $$ = makeTypeCast($1, $3, @2); }
| '+' b_expr %prec UMINUS
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", NULL,
$2, @1); }
+ | '|' b_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", NULL,
$2, @1); }
+ | RIGHT_ARROW b_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "->", NULL,
$2, @1); }
| '-' b_expr %prec UMINUS
{ $$ = doNegate($2, @1); }
| b_expr '+' b_expr
--
2.52.0
Test case says:
CREATE FUNCTION identity_int(int) RETURNS int
LANGUAGE sql IMMUTABLE AS 'SELECT $1';
CREATE FUNCTION
CREATE OPERATOR | (RIGHTARG = int, FUNCTION = identity_int);
CREATE OPERATOR
CREATE OPERATOR -> (RIGHTARG = int, FUNCTION = identity_int);
CREATE OPERATOR
SELECT | 5;
?column?
----------
5
(1 row)
SELECT -> 5;
?column?
----------
5
(1 row)
Le 18/07/2026 à 10:39, PG Bug reporting form a écrit :
> The following bug has been logged on the website:
>
> Bug reference: 19558
> Logged by: Pierre Senellart
> Email address: pierre@senellart.com
> PostgreSQL version: 19beta2
> Operating system: Linux
> Description:
>
> The following works on PostgreSQL <= 18 but raises a syntax error on
> 19beta1/19beta2 (tested: PostgreSQL 19beta2, Ubuntu package
> 19~beta2-1.pgdg26.04+1, x86_64-linux):
>
> CREATE FUNCTION identity_int(int) RETURNS int
> LANGUAGE sql IMMUTABLE AS 'SELECT $1';
> CREATE OPERATOR | (RIGHTARG = int, FUNCTION = identity_int);
> CREATE OPERATOR -> (RIGHTARG = int, FUNCTION = identity_int);
>
> SELECT | 5; -- 18: returns 5; 19beta2: syntax error at or near "|"
> SELECT -> 5; -- 18: returns 5; 19beta2: syntax error at or near "->"
>
> Cause: the SQL/PGQ property graph patch turned "|" and "->" into dedicated
> grammar tokens (RIGHT_ARROW), declared in the precedence list alongside Op.
> Explicit binary productions (a_expr '|' a_expr, a_expr RIGHT_ARROW a_expr)
> preserve infix use, and both tokens were added to the operator-name
> productions, so binary use and the OPERATOR() syntax still work:
>
> SELECT OPERATOR(public.|) 5; -- still returns 5 on 19beta2
> SELECT OPERATOR(public.->) 5; -- still returns 5 on 19beta2
>
> But no unary counterparts of these productions were added, so a user-defined
> *prefix* operator spelled exactly "|" or "->" can no longer be invoked by
> its bare name. Note the inconsistency: CREATE OPERATOR still accepts both
> names for prefix operators; the resulting operator just cannot be called
> except through OPERATOR().
>
> If the tokenization is here to stay, could unary productions ('|' a_expr,
> RIGHT_ARROW a_expr) be added to restore the pre-19 behaviour? Failing that,
> this seems worth an entry in the release notes' incompatibilities section,
> since nothing currently documents it.
>
> Motivation: https://pgxn.org/dist/provsql/ which I am developing uses prefix
> | as a probabilistic “given” operator. This works on all PostgreSQL versions
> from 10 to 18, but fails on 19beta2.
>
>
>
>
Attachments:
[text/x-patch] 0001-bug-19558-Fix-user-defined-prefix-operators-and.patch (1.8K, ../02aea982-c656-462d-a412-1fb2e388f754@gmail.com/2-0001-bug-19558-Fix-user-defined-prefix-operators-and.patch)
download | inline diff:
From e7032368270b9ac58698e9249f766739b66c848a Mon Sep 17 00:00:00 2001
From: Pierre Forstmann <pierre.forstmann@gmail.com>
Date: Sat, 18 Jul 2026 17:33:33 +0200
Subject: [PATCH] bug#19558: Fix user-defined prefix operators '|' and '->'
---
src/backend/parser/gram.y | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/src/backend/parser/gram.y b/src/backend/parser/gram.y
index ff4e138..331da79 100644
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@@ -15873,6 +15873,10 @@ a_expr: c_expr { $$ = $1; }
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", NULL, $2, @1); }
| '-' a_expr %prec UMINUS
{ $$ = doNegate($2, @1); }
+ | '|' a_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", NULL , $2, @1); }
+ | RIGHT_ARROW a_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "->", NULL , $2, @1); }
| a_expr '+' a_expr
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", $1, $3, @2); }
| a_expr '-' a_expr
@@ -15902,6 +15906,7 @@ a_expr: c_expr { $$ = $1; }
| a_expr '|' a_expr
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", $1, $3, @2); }
+
| a_expr qual_Op a_expr %prec Op
{ $$ = (Node *) makeA_Expr(AEXPR_OP, $2, $1, $3, @2); }
| qual_Op a_expr %prec Op
@@ -16355,6 +16360,10 @@ b_expr: c_expr
{ $$ = makeTypeCast($1, $3, @2); }
| '+' b_expr %prec UMINUS
{ $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "+", NULL, $2, @1); }
+ | '|' b_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "|", NULL, $2, @1); }
+ | RIGHT_ARROW b_expr %prec UMINUS
+ { $$ = (Node *) makeSimpleA_Expr(AEXPR_OP, "->", NULL, $2, @1); }
| '-' b_expr %prec UMINUS
{ $$ = doNegate($2, @1); }
| b_expr '+' b_expr
--
2.52.0
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Message-ID: <02aea982-c656-462d-a412-1fb2e388f754@gmail.com>
Permalink: ../02aea982-c656-462d-a412-1fb2e388f754@gmail.com/
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To: pgsql-bugs@postgresql.org
Cc: pierre.forstmann@gmail.com, pierre@senellart.com, pgsql-bugs@lists.postgresql.org
Subject: Re:[patch] BUG #19558: User-defined prefix operators "|" and "->" no longer parse in 19beta2 (SQL/PGQ grammar change)
In-Reply-To: <02aea982-c656-462d-a412-1fb2e388f754@gmail.com>
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